The present invention relates to a microbiological process for preparing 11.beta.,21-dihydroxy-2'-methyl-5'.beta.H-1,4-pregnadieno(16,17-d)-oxazole -3,20-dione, which is useful as a well known antiinflammatory active corticoide.
The microbiological .DELTA..sup.1 -dehydrogenation of 11.beta.,21-dihydroxy-2'-methyl-5'.beta.H-4-pregneno(16,17-d)-oxazole-3,20 -dione cannot be conducted as readily as that of other steroids. This has been determined by recent experiments. The fermentation of this compound with living cultures of conventional steroid -.DELTA..sup.1 -dehydrogenating agents, such as Bacillus lentus ATCC 13 805, Bacillus sphaericus ATCC 7054, ATCC 7055, and ATCC 12 488, Bacillus subtilis NRRL B 558, as well as Norcardia corallina ATCC 4273 and 4275 produces unsatisfactory results. Hardly any conversion of the substrate is observed, and the substrate is greatly metabolized.